The principal objective of this research program is to develop an understanding of the control mechanisms that regulate immunoglobulin gene expression. To achieve this objective, we are employing an approach that compares the "normal" and "altered" gene expressions through the use of suppression and auto-immunization techniques. In the past year, we have succeeded in the induction of auto anti-allotype antibodies in homozygous allotype-suppressed rabbits, and thus have developed a new procedure for the induction of a homozygous allotype-suppressed litter. With this new procedure, we have an easier and more reliable technique for inducing various "altered" expressions of rabbit immunoglobulin genes. Currently, two experiments are being done. One is to observe the compensatory effects of allotype suppression, when the expression of two major allotypic loci at a trans-chromosomal region is simultaneously suppressed in heterozygous rabbits. A likely result of this suppression will be enhanced levels of so-called "recombinant" Ig molecules and/or the Ig molecules bearing the so-called "latent" allotypes. The other experiment is a comparison of idiotypes of two anti-Ars antibodies from the same rabbit obtained before and after the release of suppression of its VHa allotype. Also, in this research program, we are continuing the study of the complex nature of the al allotypic subspecificities of the rabbit Ig VH region. Two approaches are used in this study; one approach is the use of "homogeneous" antibodies as the standard Ig molecules that bear a specific al allotypic subspecificity, and the other is the use of the sequential release of Ig subpopulations from allotype suppression.